MR850 Model Number

Supply Voltage

Fuse Type

Part Number

MR850Jxx

115 V~

F1: 1 A 250 V FastBlow

999 830 001

 

 

F2: 4 A 125 V FastBlow

999 830 017

 

 

F3: 3 A 250 V FastBlow

999 830 012

 

 

F4: 3 A 250 V FastBlow

999 830 012

MR850Gxx

100 V~

F1: 1 A 250 V FastBlow

999 830 001

 

 

F2: 4 A 125 V FastBlow

999 830 017

 

 

F3: 3 A 250 V FastBlow

999 830 012

 

 

F4: 3 A 250 V FastBlow

999 830 012

WARNING:

Be sure to replace the fuse with the correct rating and type. Do not under any circumstances replace F2 with anything other than a fast blow fuse of the type and rating specified, as serious injury could result.

3.Replace fuse.

4.Close the case (section 7.2.8).

7.2.3Replacement of Printed Circuit Boards (PCBs)

1.Open the case (section 7.2.1).

2.Disconnect all harnesses attached to the power PCB. Disconnect the mains and protective earth wires by unscrewing the terminal blocks, and cutting the cable ties (Figure 7.4).

3.Remove PCBs, and using an appropriate tool, remove the ROM from the 32-pin socket on the control PCB. Store the ROM in an antistatic bag or box.

4.Unpack replacement PCBs, install the ROM from the previous PCB.

5.Replace the mains fuses (F3, F4) with the correct type, and attach mains and protective earth wires, using the cable ties provided (Figure 7.4).

6.NOTE: If revision A PCBs are being replaced with revision C PCBs or later, (look for identification on the control board), then the wiring of the heater plate thermal cutout (and thermistor) will need to be changed. Un-clip the four pins from the connector by using a small flat bladed screwdriver. Re-wire the connector so the thermistor wires (white) are located on the inner two pins, and the thermal cutout wires (black) are located on the two outer pins.

7.Connect harnesses from the transformer and heater plate to the power PCB.

8.Close the case (section 7.2.8).

9.Update the EEPROM software version (step 5, section 7.2.6).

10.Check that the humidifier powers up normally, and complete a full performance test (section 8).

MR850 Technical Manual * Revision J * Issued November 2005 * Ref. 185041340 (185041713 internal)

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